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CAS 684-93-5

N-Nitroso-N-methylurea

CarcinogenTeratogen

N-Nitroso-N-methylurea (also called methyl nitrosourea, MNU) is a highly toxic, DNA‑damaging chemical used mainly in research labs. Everyday exposure for the public is very unlikely [1][2].

Where It Comes From

Made and used in laboratories; unstable and not used in consumer products. Rarely, it may form via nitrosation reactions under certain conditions [1][4].

How You Are Exposed

Mostly at work—handling powders/solutions, inhaling aerosols, or skin/eye contact during lab tasks or spills [2].

Why It Matters

Strong mutagen that causes cancers in many animal organs; can burn eyes/skin and cause acute illness. Expert reviews flag it as a carcinogenic hazard to humans [1][2].

Who Is at Risk

Lab and production workers handling nitrosoureas; pregnant workers; anyone without proper ventilation and protective gear [2][1].

How to Lower Your Exposure

If you work with it, use closed systems and fume hoods, double gloves, eye/face protection, and strict storage/spill procedures; get training and medical monitoring [2]. For the public, exposure is unlikely; lowering overall N‑nitroso exposure (e.g., limiting nitrite‑cured meats, avoiding tobacco smoke) can help [3][4].

References

  1. [1]IARC. Some N‑Nitroso Compounds. IARC Monographs, Vol. 17. International Agency for Research on Cancer.
  2. [2]WHO/ILO. International Chemical Safety Card (ICSC) 0954: Methylnitrosourea.
  3. [3]ATSDR. Nitrosamines ToxFAQs. Agency for Toxic Substances and Disease Registry.
  4. [4]IARC. Ingested Nitrate and Nitrite, and the Evaluation of Endogenous Formation of N‑Nitroso Compounds. IARC Monographs, Vol. 94.

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